I personally prefer Cyclades (now part of Avocent) console servers since they run Linux and I can use vi to edit configuration files. The only problem is that Cyclade's console servers come with only one Ethernet port. What if a switch to which Cyclade console server is connected via Ethernet dies and you need to access its console to figure out what is going on? You can always hook up modem to you console server and dial in, but in this case only one person can connect and with proliferation of VoIP analog phone lines in offices are getting hard to come by.
So, after some search I found Perle's IOLAN console server which have 2 Ethernet ports. These ports can be used in Active/Standby configuration, meaning you can assign 1 IP address and when 1st Ethernet port goes down, IOLAN moves this IP address automatically to second port. For this feature alone I am willing to tolerate their Windows configuration client software.
Now I need to connect IOLAN to F5 LTM/GTM console. Since LTM's console is DB9 male connector and IOLAN is RJ45, I need RJ45-DB9 female converter. I buy these converters at pccables.com. The wires in that converter on RJ45 side are connected like this:
I need to plug those wires into DB9 side of the converter like this
Now, take regular straight network cable, plug one end into RJ45-DB9 converter, another into IOLAN port. Done. Do not forget that by default IOLAN's port speed is 9600 and F5's is 19200.